1. Field of the Invention
The present invention relates to a method for manufacturing a fuel filter arrangement that removes undesirable foreign particles or objects from fuel. The present invention also relates to such a fuel filter arrangement.
2. Description of Related Art
When fuel, which contains undesirable foreign particles or objects, is supplied to a corresponding device, such as a fuel injector of an internal combustion engine, the foreign particles may prevent proper operation of the device. Specifically, for example, when the foreign particles contained in the fuel are caught in a valve of the fuel injector, the valve of the fuel injector cannot be closed completely, so that fuel is kept injected through the valve of the fuel injector. To address such a disadvantage, it is possible to arrange a fuel filter in a fuel passage connected to the fuel injector to remove the foreign particles from the fuel. Furthermore, in order to remove the foreign particles of different sizes, it has been proposed to arrange a filter of a relatively large pore size at an upstream side of the fuel passage and a filter of a relatively small pore size at a downstream side of the fuel passage. Furthermore, it has been proposed to form a fuel filter from a filter paper, which is folded.
However, placement of more than one fuel filter in the fuel passage causes an increase in a number of components and an increase in a number of seals between the fuel filters and the fuel passage, resulting in an increase in a number of assembling steps of the fuel filters. In order to address such a disadvantage, it has been proposed to provide a single fuel filter arrangement, which includes a filter of a relatively large pore size and a filter of a relatively small pore size. The filter of the relatively large pore size is arranged on a fuel inflow side of the fuel filter arrangement, and the filter of the relatively small pore size is arranged on a fuel outflow side of the fuel filter arrangement. With this fuel filter arrangement, it is possible to reduce a number of components and a number of seals.
However, in the previously proposed method where each fuel filter is formed by folding the filter paper made of the fibers, it is difficult to form a single fuel filter arrangement of a desired shape, which includes the filter of the relatively large pore size and the filter of the relatively small pore size joined together. Furthermore, when the fuel filter arrangement is formed of the filter papers, support plates need to be arranged on opposed axial ends of the fuel filter arrangement to support the fuel filter arrangement.